Apparatus for wireless telegraphy and telephony



Nov. 20, 1923- 1,474,382

H. J. ROUND 1 APPARATUS FOR WIRELESS TELEGRAPHY AND TELEPHONY Filed March 51, 1920 whim a dW 1 WW7 Patented Nov. 20, 1923.

UNITED STATES.

PATENT oFFlcE."

HENRY JOSEPH ROUND, OF LONDON, ENGLAND, ASSIGNOR TO THE RADIO CORPORA- TION OF AMERICA, OF NEW YORK, N. Y., A CORPORATION OF DELAWARE.

APPARATUS FOR WIRELESS TELEGRAPHY AND TELEPHONY.

To all whom it may concern:

Be it known that I, HENRY J osnrn ROUND, a subject of the King of Great Britain, residing at 9 Woodberry Crescent, Muswell Hill, London, England, have invented new and useful Improved Apparatus for Wireless Telegraphy and Telephony, of which the following is a' specification. v

In apparatus comprising three electrode 10 valves dependent for their working upon the mere change ofpotential of the rids troubles frequently arise owing to thee ects of parasitic capacities.

In order to obtain maximum sensitiveness the maximum potential obtainable from the available energy is usually applied to the grid. This is done by connecting the grid to one end of a winding of minimum selfcapacity, the other end of which is connected to the battery which heats the filament. The

capacity of this battery is of course larger than that of the grid and in consequence a change of charge in a neighbouring, aerial gives rise to reater variations of potential at the grid en of the winding than at the battery end thereof so that a difference of potential is created between the ends of the winding no matter what. is the cause of the initial variation in charge.

According to this invention the winding is enclosed in a metal screen or sheath so arranged as not to form a completely closed circuit, and the sheath is connected to the battery which heats the filament. The effect 5 of this arrangement is that no difference of potential as mentioned above will occur.

I The invention is. illustrated by. the accompanying diagram. A is an aerial system including a var1able".condenser B and the primaryv C'. of a transformer of which the secondar D is connected to a condenser E andvto t e grid and filament of a valve F. The winding D may be so arranged that its self-capacity is a minimum. Around this windin 7 metal 5 eet bent so that its edges nearly but not quite meet and connected to the filament battery H. v The anode and filament of the valve F are connected as is usual to an inductance I and a b t ry v In direction finding work when using is placed a sheath G formed of a frame aerials the forced currents produced in the frame system acting as a plain vertical aerial through its capacity to earth are liable to give a potential difference between the grid and filament. This potential difference being independent of the direction of the.

frame distorts the normal frame diagram.

By the insertion between the frame and the coil attached to the receiver of the above.

commonly connected across the aerial tuning inductance. This arrangement simplifies tuning, but has the disadvantage Ofpermitting very short forced waves to. affect the grid, the inductance being much toogreat an impediment for them. The effect of these short waves is eliminated by employing a metal sheath as beforesaid connected to the valve battery and arranged in between the two windings ofa tightly coupled transformer, of, say 1/1 ratio.

In both these arrangements the invention is of especial value in aeroplane work where ma eto induction is a serious matter. 7

at'I claim is v 1. In a wireless receiver, the combination with an aerial circuit containing a primary winding of a secondary winding, a condenser connected across the ends of the secondary Winding, a valve containing a filament, a grid and an anode, the filament and grid being connected in series with the secondarv winding, a battery adapted to heat the filament and a metal sheathgsurrounding the secondary winding and connected to the battery.

2. In a wireless receiver, the combination with an aerial circuit containing a primary winding, ofasecondary winding, a condenser connected across the ends of the secondary winding, a valve containing a filament, a rid and an anode, the filament. and id bein connected inseries with the secon ary win ing, a battery adapted to heat the filament and a slotted metal sheath surrounding the secondary winding and connected to the battery.

. HENRY JOSEPH ROUND, 

